SKELETAL SYSTEM AND ITS FUNCTIONS

 SKELETAL SYSTEM AND ITS FUNCTION:

Introduction:

  • The adult human skeletal system consists of 206 bones as well as network of tendons, ligaments and cartilage that connects them.
  • The skeletal system performs such functions like; support, movement, protection, blood cell production, calcium storage and endocrine system that enable us to survive.
  • Animals with internal skeletal made up of bones called vertebrates, are actually the minority on earth. As much as 98% of all animals are invertebrates, meaning they don’t have internal skeletons or backbones.
  • The skeletal system consists of the different bones in the body and this system forms the framework of the body. For example; movements such as throwing a ball, typing and walking require the coordinated use of bones and muscles.
  • Blood vessels and nerves run parallel to bones; they are located more easily if the bones are identified first.
  • The number of bones a person is born is not final. Human infants are born with about 300 bones. By the time humans reach adulthood, they have 206 bones
  • Human males grow until their late teens and females grow until 2 years after the beginning of their menstrual cycle. This is when the growth plates on bones usually close, halting bone expansion.
  • The skeletal of adult male and females have some variation, primarily to accommodate childbirth. The female pelvis is flat, more rounded and proportionally larger. For example; a male pelvis is about 90° or less of angle whereas female is 100° or more.
  • Teeth are considered to be a part of the skeletal system but they are not counted as bones. Teeth are made up of dentin and enamel; enamel is the strongest substance of our body.

HUMAN SKELETAL SYSTEM:

The human skeletal system is made up of bones and cartilage. There are total of 206 bones in the human body. They are divided into axial and appendicular skeleton. The axial skeleton consists of bones that are found towards the center of the body including skull, vertebrae and the sternum. The appendicular skeleton consists of bones that are found in the extremities.

                                            

Types of skeletal system:

The basic structure of human body is skeletal system. The entire body is built around the hard framework of skeleton. Skeletal system has two distinctive parts; axial skeleton and appendicular skeleton:

  1. Axial skeleton: 
  • Axial skeleton has total of 80 bones, which consists of vertebral column, the rib cage and the skull.
  • The axial skeleton transmits the weight from the head, trunk and the upper extremities down to the lower extremities at the hip joints.
  • This weight transmission helps the human to maintain our upright position.

                                                

  1. SKULL:
  • Mandibles
  • Occipital bones; two temporal bones, 2 parietal bones, sphenoid bones, ethmoid and frontal bones.
  • Vomer: 2 nasal conchae, 2nasal bvones, 2 maxillae, the mandible, 2 palatine bones, 2 zygomatic bones, 2 lacrymal bones.
  • The occipital, parietal, frontal in the neuro-endocranium and the nasal, lachrymal and vomer.
  1. VERTEBRAE: Specific vertebrae are corresponding to their area as well as location. The vertebrae from highest to lowest.
  2. Cervical spine: 7 vertebrae(c1-c7)
  3. Thoracic spine: 12 vertebrae (T1-T12)
  4. Lumber spine: 5 vertebrae (L1-L5)
  5. Sacrum: 5 (fused) vertebrae(S1-S5)
  6. Coccyx: 4 (3-5) fused vertebrae (tailbone)
  7. RIB CAGE: It contain 24 ribs that are made up of ribs; 12 pairs of ribs on each side.
  8. Appendicular skeleton:

                                                       

  1. It has total of 126 bones and is made up by pectoral girdles, the upper limbs, the pelvic girdles and the upper and lower limbs.
  2. The function of appendicular skeleton is to make walking, running and other movements possible to protect from major organs which are responsible for digestion, excretion and reproduction.
  3. It split into 6 main regions:
  4. Pectoral girdles (4 bones): Left and right clavicle (2) and scapula (2).
  5. Arms and forearms (6 bones): Left and right humerus (2) arm, ulna (2) and radius (2) forearm.
  6. Hands (54 bones): left and right carpels (16) wrist, metacarpels (10), proximal phalanges (10), intermediate phalanges (8) and distal phalanges (10).
  7. Pelvis (2 bones): left and right hip bone (2).
  8. Thighs and legs (8 bones): left and right femur (2) thigh, patella (2) (knee), tibia (2)and fibula (2) leg.
  9. Feet and ankles (52 bones): left and right tarsals (14) ankle, metatarsals (10), proximal phalanges (10), intermediate phalanges (8) and distal phalanges (10).

Function of the skeletal system:

There are some functions of the skeletal system that are listed below:

  1. Support: It provides a framework that supports the body and facilitates movement and maintains the anatomical shape. The presence of firm bony skeleton allows the organisms to have distinctive shape adapted towards a particular lifestyle. For example; in a fast moving animal like cheetah the skeleton contains long, thin bones and an extremely flexible spine. The structure of the skeleton also allows it to absorb the impact of running at high speed.
  2. Shape: Skeletal system gives shape to our bones and keeps the internal organs at their place. Skeletal system gives shapes to the body. For example vertebral column keeps our body erect.
  3. Protection: Skeletal system protects the inner delicate organs of our body. It acts as a very strong shield that provides protection to the rest of the body organs. This is an essential function of the skeletal system, for without specific bones such as the skull or ribs the internal structure would collapse. This system protects the important internal organs such as heart, lungs, brain etc.  For example;
  4. Skull protects the brain
  5. Vertebrae protects the spinal cord
  6. Rib cage, sternum and spine protect vital internal organs like heart and lungs.
  7. Movement:  The skeleton in conjuction with muscles, ligaments and tendons allow for movement. The range of movement is determined by the type of joint and through the coordination of the nervous system. Bones serves as attachment surfaces for muscles and thus provides suitable level for locomotion.
  8. Blood cell production: Blood cells are produced within the skeletal structure. Blood cells develop from haematopoietic stem cells and are formed in the bone marrow through the highly regulated process of haematopoiesis. Haematopoietic stem cells are capable of transforming into RBS, WBC and platelets.  Bone marrow is found in the hollow cavity of long bones which produces RBCs. These stem cells can be found circulating in the blood and bone marrow in people of all ages as well as in the umbilical cord of the newborn babies.
  9. Storage of minerals or Mineral haemostasis: Bone tissues have several minerals including calcium and phosphorous, when required the bone will release the minerals into the blood thus facilitating the balance of minerals in the body.
  10. Endocrine regulation or storage of chemical energy: Bone cells release a hormone called osteocalcin which contribute to regulate the level of blood sugar (glucose) and fat deposition. It serves as an important chemical energy reserve.
  11. Flight: Hollow and light bones of birds are the peculiar feature that helps the birds in flying. This creates a streamlined body which is adapted for flight.
  12. Sexual dimorphism: Many animals have sexual dimorphism in their skeleton. In humans, while this sexual dimorphism is fairly limited, there are differences in the angle of pelvic bones to accommodate pregnancy. Even invertebrates like snails and prawns often have hard endoskeletons to protect themselves from predators.

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